It is known that concrete blocks may be cast in cavities in, for example, a resilient polyurethane mold. For blocks having straight sides, the mold may be inverted and the blocks release onto a support or collection surface. However, when the blocks have intricate surfaces, it can be difficult to separate or demold the blocks from the mold. Manthei et al. U.S. Pat. No. 7,618,578 shows a process for demolding large cast concrete blocks from a resilient mold where the blocks have, for example, exterior surfaces shaped to simulate weathered natural stone blocks. These blocks may have sufficiently deep surface grooves, recesses and projections which make it difficult to demold. According to that patent, the resilient mold in which the blocks are cast is supported in a rigid frame during the casting and curing steps. Corners of the mold are tethered to the support frame to allow the mold to drop a limited distance from the frame when the frame and mold are inverted. In operation, a concrete block is cast in the mold. After the block has cured, a forklift or other apparatus is used to pick up the frame, mold and block. While being held together, the frame, mold and block are then inverted. While supporting the block, the frame and mold are lifted, allowing the resilient mold to be suspended from the frame by the tethers. The weight of the block causes the resilient mold to bend and stretch sufficiently to release the block. The block is then set on a pallet or other support surface, and the frame and mold are turned upright so that they are ready for use in casting another block. This process for demolding blocks relies on the weight of the block to cause the mold to bend. It is more difficult for demolding smaller, lighter weight blocks with irregular surface shapes which may retain the blocks in the mold.